2008 68rfe weird problem

[ruben121]

I got a weird one for the 68s savvy , I built a 2008 68 for my customer that came in burnt and would barely move in first .

 

long story short I built it with a ton of upgrades and everything is upgraded and gone through, vacuumed tested etc . After installing it and took it for a test drive it has no tcc lockup and it wouldn’t shift to 6th unless you release the pedal all the way , it also set code p0740 code at 10 miles of driving . I relearned the transmission and drive 32 miles with no code but same issues of no tcc engagement and only 6th by releasing the throttle pedal. 

 

Believing I did everything right ,I dropped the trans and installed another new  torque converter but that didn’t fix the issue so I pulled the trans for the second time and went through the pump and vb to try to find something but no luck , everything looked good and where it supposed to be with all the valves moving freely and everything passing vacuum test and torqued to spec with no luck. I replaced the solenoid pack with a new oem then relearned the transmission again with no luck and same issue as before with code p0740 back again.

 

any ideas or help would be appreciated, for right now I’m going to pull the pan and replace the vb with a good core then if that don’t I’ll drop the trans and replace the pump with a good core . 

[Mopar1973Man]

P0740-TCC OUT OF RANGE

 

For a complete wiring diagram Refer to Section 8W.

 

• When Monitored:
The Torque Converter Clutch (TCC) is in FEMCC or PEMCC, Transmission temperature is hot, Engine temperature is greater than 38° C or 100° F, Transmission Input Speed greater than engine speed, TPS less than30°, and brake not applied.

• Set Condition:
The TCC is modulated by controlling the duty cycle of the L/R Solenoid until the difference between the Engine RPM and the Transmission Input Speed RPM or duty cycle is within a desired range. The DTC is set after the period of 10 seconds and 3 occurrences of either: FEMCC - with slip greater than 100 RPM or PEMCC - duty cycle greater than 85%.

 

Possible Causes
RELATED L/R SOLENOID OR PRESSURE SWITCH DTCS PRESENT INTERNAL TRANSMISSION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

 

Theory of Operation
When in 2nd, 3rd, or 4th gear, the torque converter clutch (TCC) can be locked or partially locked when certain conditions are met. The TCC piston is electronically modulated by increasing the duty cycle of the LR/TCC solenoid until the torque converter slip difference (difference between engine and turbine speed) is within 60 RPM. Then the LR/TCC solenoid is fully energized (FEMCC / 100% duty cycle). Torque converter slip is monitored in FEMCC to
ensure adequate clutch capacity. The transmission will attempt normal EMCC operation (not in Limp-in) even after the MIL is illuminated. MIL will illuminate after 5 minutes of accumulated slip in FEMCC.

 

Diagnostic Test
1. CHECK IF RELATED DTCS ARE PRESENT
With the scan tool, read Transmission DTCs
Are the DTCs P0750 and/or P0841 present also?
Yes>> Refer to the Transmission category and perform the appropriate symptom.
No>> Go To 2

 

2. CHECK IF THE DTC IS CURRENT
Ignition on, engine not running.
With the scan tool, record and erase DTCs. Drive the vehicle until it is fully warmed up to at least 43° C (110° F). Perform the following step 3 times.
Drive the vehicle at 50 mph and allow 4th gear to engage for at least 10 seconds. Close the throttle, then tip back in until the throttle angle is between 25 and 29 degrees. Note that if you go over 30 degrees, you must back off of the throttle and retry.
Did the TCC engage during any of the attempts?
Yes>> Go To 3
No>> Perform the Hydraulic Pressure test per the Service Information and repair the internal transmission components and Torque convertor as necessary.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)

 

3. INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set the DTC are not present at this time. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
Wiggle the wiring and connectors while checking for shorted and open circuits. This DTC can also be set under extreme temperature conditions. This is usually caused by an internal problem. Verify if the problem is only experienced under extreme hot or cold conditions. With the scan tool, check the DTC EVENT DATA to help identify the conditions in which the DTC was set. Check for Service Information Tune-ups or Service Bulletins for any possible causes that may apply.
Were there any problems found?
Yes>> Repair as necessary.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/ TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
No>> Test Complete.

Edited February 27, 2023 by Mopar1973Man